Can't be Obama. He doesn't ever make mistakes. Has to be GWB.

It is a well known fact that the Desert Putty bug finds fire detection wiring delicious....

A Swissair crew tried that, it didn't go well.

Can a 747 not land overweight?


Cargo fires in a 747 usually haven't ended well. South African 747 combi, Asiana cargo 747, UPS 747, all ended up in fatal crashes. Although a fully pax jet is a different story than a freighter, does the pax airline carry hazmat? Is it loaded in that cargo bin? There are too many questions to just assume there's no fire. And if your gauge for measuring is cabin crew finding smoke or fire in the cabin, from a fire source originating in the cargo bin, by then you are already in serious trouble.

I didn't notice that! Heck of a week with some head scratching events.

I knew Richard jinxed us with his comments in May to Wall Street.

There's a big difference between landing an A320 overweight and an overweight 747-400.

I don't know which model aircraft this was, so we'll just be using generic Boeing numbers of MTOW of 910,000# and MLW of 652,000#. Right there there's a difference of 258,000#.

Assuming the aircraft took off near max takeoff weight and flew for less than two hours, burning 25,000pph, that still leaves an additional 200,000 that needed to be dealt with before a safe landing could be made. All of it in the form of highly flammable liquid, which tends to get messy when getting spread out on a runway at 140 knots due to ruptured fuel lines and broken wings and whatnot.

Boeing builds them good, but not 200,000 additional pounds good.

Which is why the Whale has fuel dump valves and Fifi does not. You can pop an engine on Fifi at MTOW, turn around and land overweight; it's just a logbook entry (plus associated maintenance inspections.)

You try that stunt on a widebody and people will die. Ever try to evacuate an airplane when it's surrounded by burning jet fuel?

You mentioned a list of cargo fire incidents, pointing out that they all ended poorly, and you're correct they did. But they all had one glaring difference to this particular Delta flight; they all had indication of fire followed by confirmation of fire.

The Delta flight only had indication of fire. At this time there is no evidence to support a theory that there was actual smoke, heat or associated other smells that would confirm the fire indication.

It's not a question of simply "assuming" that there's no fire. Fire produces heat and smoke, and lots of it. If there had been a fire both would have been present in the cabin (and flight deck) and the aircraft would have diverted for an immediate landing. (This was a U.S. trained crew after all; had it been an Asian crew then all bets are off.)

Since we don't know what the actual weights were for takeoff, it's safe to assume that this particular flight was anywhere between 100,000 to 200,000 pounds over max landing weight during the incident.

It appears the captain did exactly the right thing delaying the landing, as there was no confirmation of fire, at any time. Had just one of the flight attendants smelled smoke or felt heat, or the flight crew detected smoke in the cockpit, the captain would have risked an overweight landing no doubt. But by getting no positive confirmation of fire, he did the right thing and prevented a potential landing catastrophe.

As for your last comment,

That my friend, is called effective use of CRM. Using all available resources to make a decision, not just a flashing light in the cockpit.

Boeing seems to disagree. 747-400 AFM has landing performance tables up to and including MTOW. 400B ~ 7,100ft @ 900,000lbs

My comment was tongue in cheek regarding landing above max landing weight.

You're being dramatic without acknowledging what is required for certification of an aircraft. What are you talking about "not 200,000 lbs" good? An aircraft that comes a smoking pile landing at close to max landing weight will not be certified. Observing the published flap speeds, recommended flap setting, appropriate approach speed, and minimal sink rate (grease it on) at touchdown...

http://www.boeing.com/commercial/aer...icle_03_3.html

"
Overweight landings are safe because of the conservatism required in the design of transport category airplanes by FAR Part 25.

FAR criteria require that landing gear design be based on:

* A sink rate of 10 feet per second at the maximum design landing weight; and
* A sink rate of 6 feet per second at the maximum design takeoff weight.

Typical sink rates at touchdown are on the order of 2 to 3 feet per second, and even a “hard” landing rarely exceeds 6 feet per second. Additionally, the landing loads are based on the worst possible landing attitudes resulting in high loading on individual gear. The 747-400 provides an excellent example. The 747-400 body gear, which are the most aft main gear, are designed to a 12-degree nose-up body attitude condition. In essence, the body gear can absorb the entire landing load. The wing gear criteria are similarly stringent: 8 degrees roll at 0 degrees pitch. Other models are also capable of landing at maximum design takeoff weight, even in unfavorable attitudes at sink rates up to 6 feet per second. This is amply demonstrated during certification testing, when many landings are performed within 1 percent of maximum design takeoff weight.

When landing near the maximum takeoff weight, flap placard speeds at landing flap positions must be observed. Due to the conservative criteria used in establishing flap placard speeds, Boeing models have ample approach speed margins at weights up to the maximum takeoff weight (see fig. 1).
"




Absolutely nothing to do with a plane being a Fifi or a whale.

http://www.boeing.com/commercial/aer...icle_03_2.html

FAR 25.1001 — Requires a fuel jettison system unless it can be shown that the airplane meets the climb requirements of FAR 25.119 and 25.121(d) at maximum takeoff weight, less the actual or computed weight of fuel necessary for a 15-minute flight comprising a takeoff, go-around, and landing at the airport of departure.

To comply with FAR 24.1001, the 747 and MD-11, for example, require a fuel jettison system. Some models, such as the 777 and some 767 airplanes have a fuel jettison system installed, but it is not required by FAR. Other models such as the DC-9, 717, 737, 757, and MD-80/90 do not require, or do not have, a fuel jettison system based on compliance with FAR Part 25.119 and 25.121(d).




Aft cargo smoke indication? Assuming that's a fire in the aft cargo hold, why wait until the cabin crew says yes the cabin shows smoke? By then the fire could reach critical components/wiring.

Gringo, I think Shy makes some pretty good points here. With a fire indication and an actual fire, 5 minutes could mean losing the ability to control the airplane. Whereas an overweight landing if executed properly should cause hot brakes and some MX inspections, not a burning catastrophe. I'm not second guessing the crew because I wasn't there, but isn't the overweight landing scenario you're describing a little bit dramatic?

Also maybe some whale drivers can chime in here, but a 74 doing a trans Atlantic wouldn't be that heavy (relatively) would it?

-HP

Very roughly, max ZFW is 532,000 lbs. and it burns 22,000 lbs. per hour, meaning the TOW would have been about 752,000 lbs. if it had ten hours endurance. Max TOW is about 860,000 lbs. and max LW is about 638,000 lbs. The aft cargo compartment has smoke detectors, not fire detectors, so it would be very likely for the smoke signal to persist for a long time after activation of the halon, and they have been known to give false smoke signals due to the presence of dust or mist in the air (probably sand, too). Although I have landed the sim way, way over MLW, and it does fine, I think this crew did the right thing - the proof being of course that they were right, there was no fire to put out after landing.